Tantalum oxide, specifically tantalum pentoxide (Ta.sub.2 O.sub.5), is a desirable material for dielectrics in semiconductor devices because of its high dielectric constant of about 25. This high dielectric constant allows tantalum pentoxide devices to occupy a much smaller area than silicon dioxide devices, for example, such as when tantalum pentoxide dielectrics are used in the formation of capacitors in integrated circuit memory devices. Further, tantalum pentoxide dielectrics have also been used in gate insulating films for the formation of transistors in integrated circuit devices to achieve high transconductance.
Capacitors are becoming increasingly important in microelectronic devices. For example, microelectronic capacitors are widely used in integrated circuit memory devices, such as dynamic random access memory (DRAM) device, static random access memory (SRAM) devices, etc. As the integration density of memory devices continues to increase, memory devices having larger per-unit area capacitance are often needed to compensate for the reduced memory device size. Use of high dielectric constant materials, such as tantalum pentoxide, has been used to increase per-unit area capacitance to obtain larger capacitance with reduced capacitor size.
As is well known, a capacitor generally includes a first conductive electrode and a second conductive electrode with a dielectric material therebetween. For example, a high dielectric material such as tantalum pentoxide may be positioned between two conductive electrodes formed of materials, such as titanium nitride, polysilicon, platinum, or any other suitable conductive electrode material.
During formation of high dielectric constant structures, such as capacitor structures, typically dry etching is performed to etch layers of the high dielectric material and the conductive electrode materials to form a capacitor structure. The dry etching of such layers generally results in a conductive etch residue which must be removed prior to subsequent processing. For example, such conductive etch residue may be a polymeric residue including tantalum, titanium, chlorine, and carbon therein when layers such as titanium nitride and tantalum pentoxide are patterned using photoresist and a chlorine containing plasma etchant.
If the conductive etch residue is not effectively removed, various operating failures may occur. For example, such conductive etch residue may cause a short between the first and second electrodes of a capacitor structure.
Various wet or aqueous cleaning solutions are available for cleaning semiconductor-based structures. For example, an SC1 clean, an SC2 clean, a piranha clean, a buffered oxide etch solution, and other fluorine-based wet chemistries have been used for cleaning residues from structures. However, such cleaning solutions are ineffective for cleaning conductive etch residues for high dielectric structures. Such cleaning solutions fail to clean the conductive etch residues without attacking the high dielectric structures, such as capacitor structures.